1. Field
One embodiment of the invention relates to a detection apparatus of a still subtitle included as a part of a picture or image in a video signal, visual equipment which displays an image including a still subtitle, and a processing method of an image including a still subtitle.
2. Description of the Related Art
A video signal of a movie often includes a still subtitle. Such a video signal may be, for example, a videoized signal (30 frames/s or 60 fields/s) produced by telecine-converting a movie film (24 frames/s) with a subtitle and applying 2-3 pull-down processing to the converted signal, or a videoized signal produced by superimposing a subtitle picture onto a telecine-converted movie film picture. Upon generating interpolating frames of pictures or images of such video signal including a still subtitle, a subtitle part is often disturbed by generating interpolating pixels of the subtitle part using wrong vectors. That video signal is visually undesirable when noise appears on the subtitle part.
In order to execute processing for reducing noise of the subtitle part of the interpolating frames, a region of a still subtitle included as a part of a picture or image in a video signal is to be detected. As methods of detecting the subtitle region, a method of detecting a subtitle region in small region (block defined by a plurality of pixels) units (cf. Jpn. Pat. Appln. KOKAI Publication No. 2008-252561), and a method of detecting a subtitle region in pixel units (cf. Jpn. Pat. Appln. KOKAI Publication No. 2009-017325) are available.
The invention of Jpn. Pat. Appln. KOKAI Publication No. 2008-252561 allows telecine processing for converting a film picture including 24 frames/s into a video picture including 30 frames/s to detect subtitle regions in a picture signal which has undergone 2-3 pull-down processing in small region (block defined by a plurality of pixels) units (see paragraphs 0004 to 0009). The invention of Jpn. Pat. Appln. KOKAI Publication No. 2008-252561 can accurately detect subtitle blocks in small region units, but cannot detect them in smaller units, i.e., in pixel units.
The invention of Jpn. Pat. Appln. KOKAI Publication No. 2009-017325 also makes detection in pixel units in extraction of a character string rectangular region (subtitle region) (see paragraphs 0018, 0019, 0030, and 0033). However, Jpn. Pat. Appln. KOKAI Publication No. 2009-017325 does not check any change of a subtitle region between neighboring frames, and is not sufficient as a detection method of a still subtitle included in a video picture (movie).